A managing director at Goldman Sachs was found dead Sunday after an apparent kiteboarding accident on Long Island, cops said.

The body of Nicholas Valtz, 39, was found floating in Napeague Harbor, according to East Hampton police.

The Brooklyn resident was an amateur kiteboarder — a growing sport that combines windsurfing and paragliding. Relatives went to look for him after he did not return from the harbor, and made the tragic discovery, cops said. Valtz’s family was staying at a summer home in Bridgehampton.

Goldman Sachs promoted Valtz to managing director in 2010, according to Bloomberg.